Portable Python is not being developed anymore. At the moment there are several better and more up-to-date alternatives:

PythonXY

Python(x,y) is a free scientific and engineering development software for numerical computations, data analysis and data visualization based on Python programming language, Qt graphical user interfaces and Spyder interactive scientific development environment.

WinPython

A free Python-distribution for Windows plattform, including prebuilt packages for Scientific Python.

Anaconda

Completely free enterprise-ready Python distribution for large-scale data processing, predictive analytics, and scientific computing

Python Anywhere

PythonAnywhere makes it easy to create and run Python programs in the cloud. You can write your programs in a web-based editor or just run a console session from any modern web browser.